Reversible Semimetal–Semiconductor Transition of Unconventional-Phase WS<sub>2</sub> Nanosheets
Wei Zhai, Junlei Qi, Chao Xu, Bo Chen, Zijian Li, Yongji Wang, Li Zhai, Yao Yao, Siyuan Li, Qinghua Zhang, Yiyao Ge, Banlan Chi, Yi Ren, Zhiqi Huang, Zhuangchai Lai, Lin Gu, Ye Zhu, Qiyuan He, Hua Zhang
Abstract
Phase transition with band gap modulation of materials has gained intensive research attention due to its various applications, including memories, neuromorphic computing, and transistors. As a powerful strategy to tune the crystal phase of transition-metal dichalcogenides (TMDs), the phase transition of TMDs provides opportunities to prepare new phases of TMDs for exploring their phase-dependent property, function, and application. However, the previously reported phase transition of TMDs is mainly irreversible. Here, we report a reversible phase transition in the semimetallic 1T′-WS 2 driven by proton intercalation and deintercalation, resulting in a newly discovered semiconducting WS 2 with a novel unconventional phase, denoted as the 1T′ d phase. Impressively, an on/off ratio of >10 6 has been achieved during the phase transition of WS 2 from the semimetallic 1T′ phase to the semiconducting 1T′ d phase. Our work not only provides a unique insight into the phase transition of TMDs via proton intercalation but also opens up possibilities to tune their physicochemical properties for various applications.